Conventionally, there has been known, as this kind of a linear movement device, a linear guide device used in a linear guide portion of a machine tool, a transferring device or the like for guiding a movable body of a table or the like on a fixed unit of a bed, a saddle or the like, a ball screw used along with the linear guide device for providing stroke of linear movement in accordance with a rotational amount of a motor to the movable body or the like.
The former linear guide device is constituted by a track rail (track shaft) arranged above the fixed unit and where a rolling groove of balls is formed in the longitudinal direction and a sliding base (slide member) having a load rolling groove opposed to the rolling groove of the track rail via a number of rolls and where an infinite circulation path of balls rolling on the load rolling groove is formed and is constituted such that the sliding base supporting the movable body is linearly moved continuously along the track rail in accordance with infinite circulation of the balls. Further, in contrast thereto, there is a case where it is constituted such that the track rail is moved relative to the fixed sliding base.
Meanwhile, the latter ball screw is constituted by a screw shaft (track shaft) where a ball rolling groove in a spiral shape is formed by a predetermined lead and a nut member (slide member) having a load rolling groove opposed to the ball rolling groove via a number of balls and where an infinite circulation path of the balls rolling on the load rolling groove is formed and is constituted such that the balls are circulated in the infinite circulation path in correspondence with relative rotational movement between the screw shaft and the nut member by which the nut member and the screw shaft are moved in the shaft direction relative to each other.
Meanwhile, in using such a linear movement device, the balls or the above-described rolling grooves and so on need to pertinently lubricate in accordance with conditions of use in view of restraining wear of the balls per se, wear of the rolling groove of the track rail or the screw shaft on which the balls roll or wear of the load rolling groove of the sliding base or the nut member and maintaining high precision movement of the slide member over a long period of time.
Conventionally, there has been known a linear guide device disclosed in Japanese Unexamined Utility Model Publication No. JP-A-7-23824 as a linear movement device having a device for supplying lubricant to balls, rolling grooves and so forth. According to the linear guide device, as shown in FIG. 19, polymer members 120 impregnating a lubricant are provided on an inner face of a sliding base 122 opposed to a track rail 121, the lubricant gradually oozing out from the polymer members 120 is coated on an upper face 123 and side faces 124 in accordance with reciprocating movement of the sliding base 122 by which the lubricant is supplied to rolling grooves 125 and balls 126.
Further, there has been known other lubricant supplying device for lubricating a track shaft of a linear movement device disclosed in Japanese Unexamined Patent Publication No. JP-A-6-307442. According to the lubricant supplying device, as shown in FIG. 20, pads 127 impregnating a lubricant are incorporated into cover frames 128 by which the pads 127 at inside thereof are brought into contact with a track rail 129 and the cover frames 128 are mounted at a front portion and a rear portion of a sliding base 130 in the movement direction such that the pads 127 are brought into sliding contact with the track rail 129 in accordance with the movement of the sliding base 130. Accordingly, when the sliding base 130 is reciprocated along the track rail 129, the lubricant oozed out from the pads 127 is coated on the surface of the track rail 129 and the lubricant is similarly supplied to rolling grooves or balls.
However, according to these lubricant supplying devices, the polymer member or the pad mounted to the sliding base is provided with both of a function as a coater for coating the lubricant on the track rail and a function as an absorber for holding the lubricant per se, a material which is optimum as the former of the coater is not necessarily a material which is optimum as the latter of the absorber and accordingly, it is difficult to stably supply the lubricant to the track rail over a long period of time.
That is, at an initial stage of start of use, the polymer member or the pad is sufficiently impregnated with the lubricant and accordingly, an amount of the lubricant excessive for lubricating the ball rolling grooves or the balls is coated on the track rail, whereas with an increase in an accumulated running distance of the sliding base in respect of the track rail, the amount of coating the lubricant to the track rail is significantly reduced and it is difficult to coat a necessary minimum amount of the lubricant for lubricating the ball rolling grooves and the balls stably on the track rail over a long period of time.
Meanwhile, although in order to coat a sufficient amount of the lubricant on the track rail over a long period of time, the polymer member or the pad may be magnified and a large amount of the lubricant may be held thereby, even when such a measure is adopted, the above-described problem in which the amount of supplying the lubricant is significantly changed in accordance with accumulation of the running distance of the sliding base cannot be resolved, or there also poses a problem in which the sliding base mounted with the polymer member or the pad is magnified and downsizing of a linear movement device cannot be achieved.